Combinations of a glass-base inorganic filler material and the polyacetal resins to improve the mechanical strength have been known. However, the polyacetal resin is poor in chemical activity and a mere combination of the polyacetal resin with the glass-base inorganic filler material followed by melting and kneading could not obtain sufficient additional strength and rather might cause declined mechanical strength than non-reinforced polyacetal resin without blending these filler materials.
Application of surface treated glass-base inorganic filler materials with such as epoxy compounds, silane compounds and titanate compounds, or combination of these compounds with the glass-base inorganic filler materials have been proposed (JP-A 62-91551 and JP-A 61-236851).
Furthermore, additions of the glass-base inorganic filler material and a boric acid compound to the polyacetal resin to improve its mechanical strength were proposed (JP-A 9-151298 and JP-A 9-176443).